Envelope shield and method of depositing metal areas



w R 1933; 7 B. c. GARDNER 3 2,107,734

ENVELOPE SHIELD AND-METHODOF,DEPOSITINGMETAL AREAS F iled May 21, 1957INVENTOR. Baa/ 2120 C GARDNER A TTORNEYS.

Patented Feb. 8, 1938 PATENT OFFICE ENVELOPE SHIELD AND METHOD OF DE-POSITING METAL AREAS Bernard 0. Gardner, Philadelphia, Pa., assignor toFarnsworth Television Incorporated, San Francisco, Calif., acorporation-of California Application May 21, 1937, Serial No. 143,942

2 Claims. My in'vention relates to. a means and method of forming metalareas in an envelope, and more particularly to a means and method ofconfining these metal areas to specific locations.

This application is a continuation-in-part of my priorapplication,Serial No. 82,915, filed June 1, 1936, entitled "Means for-forming metalareas".

Among the objects of my invention are: To provide a means and method ofconfining metal areas formed by evaporation of metal within a containerto predetermined areas of the container; to provide an expandible shieldfor an envelope which may be inverted through a narrow opening in theenvelope and expanded to cover the walls thereof in specific locations;to provide a meansand method of forming metallic mirrors and the like onspecific interior areas of an envelope" wall; and to provide a simpleremovable shield'gfor an envelope wherein metal areas a'a'e to bedeposited.

my t inventionpossessesgnumerous otherv objects and featuresoi'"advantage, somatic! which, together with the'foregoinfif wi {be setforth in the gfollowing description or -specific apparatus embodying andutilizing my It is therefore to be understood that my method isapplicable to otherapparatus, and that I do not limit myself, in anyway, to the apparatus of the present application, as I may adopt variousother apparatus embodiments, utilizing the method,

within the scope of the appended claims.

In my prior application, referred to above, I

. have described and claimed an expandible cupshaped shield that may beinserted in an envelope to cover certain definite portions of the wallthereof while metal is being evaporated therein,

to the end that the evaporated metal may be con- 1 fined to those areasof the tube not covered by the shield.

The present invention deals with a similar problem, but in this case theshield is simpler in construction and is prepared for placing within theenvelope by being rolled upon itself. The shield is made of a resilientmaterial so that it may be rolled into a small volume, inserted throughanarrow opening, andthen expanded to cover the walls of the envelope inpredetermined locations.

My. present invention isadaptedfor use on both cylindrical walls andconical walls.

My invention may be more fully understood by direct reference to thedrawing, wherein- Figure 1 is a perspective view of a cylindrical walledenvelope showing two shields; one inserted ing sizes of envelopes.

and expanded, and the other rolled preparatory to insertion.

Figure 2 is a perspective view of 'a conical walled envelope showing aninserted shield and one prepared for' insertion. v 5

Figure 3 is a sectional view and diagram showing a metallic filament inposition to evaporate metal onto the inner walls of the container shownin Figure 2, with shield in place.

Referring directly to Figure i; an envelope I 10 of glass, quartz. orsimilar non-conducting material, preferably vitreous, has a narrow neckportion 2. As it may be desirable to evaporate metal in the form of athin layer on the interior of the envelope, particularly 'on the closedend 3, 15 I prefer to insert a metallic shield within the envelope. Inthis case the metallic shield comprises a split band I of resilientmaterial, such as thin phosphor bronze, for example, which will expandto the form of a cylinder when uncon- 20 fined.

In order to insert the shield within the envelope I the split band 4 iswound into a tight roll 5 so that the diameter of the roll is less thanthe size of the opening of the narrow portion 2. The 25 roll I is thenpushed into the container, and the natural resiliency of the materialwill expand it to contact the walls of the container. It is obvious thatcontainers having different size openings and different diameters of theexpanded 30 portions may be accommodated by the use of the same splitband 4, inasmuch as the overlap 0 will be greater or less in accordancewith the diameter of the expanded portion. It is clear that the shieldmay be adjusted up and down in the 5 container to cover specific areasof the walls, and also, that the split band may be of different lengthsto accommodate long or short shielded areas.

In Figure 2, I have shown a modification of 40 my invention adapted foruse within envelopes vhaving conical walls, and here the envelope i isprovided with an expanded portion having conical walls 1 The split bandin thiscase is preferably not a rectangle, but is so shaped that when 45it is expanded to the conical shape desired, in contact with the wallsof the envelope, the upper edge will describe a circle in the envelope.Such shapes may be readily cut from metal for very- In this case, aconical 50 split band 8 is wound into a conical roll 9, having itsgreatest diameter less than the diameter of the narrow portion 2, and isinserted in the same manner as split band I, whereupon it will expand tofit the container. 55

proper location within the envelope metal may then be evaporatedtherein, as shown in Figure 3. Here, the envelope I, havng conical walls1 and conical split band 8,. is mounted on a base plate 9 and sealedthereto by a vacuum tight cement I0, such as sealing wax, for example.Extending upwardly from base plate 9' are two filament leads H passingthrough insulators 12 into the base plate, and carrying at their upperend a metallic filament M, such as'nickelor silver. The interior of theenvelope l is in contactwith a vacuum pump l5'through a vacuum'li-ne l5extending through base 9. Filament is energized by filament source l1.under the control of filae ment resistor l8;

In operation, the shield- 8,'isadjusted in the proper location withinthe tube. The narrow end 2 is sealed to the base 9 and the pump 15 isstarted to partially exhaust the air in the container to the point whereoxidation of the filament will not take place to any great extent. Afterthis amount of vacuum has been. reached .the filament H is graduallyheated by, passing" current from source I! therethroughmp'to thevaporization pointiof'r the filamentmateri'aL Atthispoint metallicvapor. is emitted and'will.de posit onthe walls of the envelope abovethe shield 8, the upper edge of the shielddrawing a sharp line ofdemarcation between the depositedv metal layer and the clearremainde'rof. the: envelope covered. by theshield." 'After a deposit of surficientthicknesshas beerrobtained on the exposed wall the envelope is let downto atmospheric pressure, removed from the base plate, and the shieldremoved by re-rolling and withdrawing through the opening. The envelopemay then be utilized as desired, as a lamp, for example, or as a cathoderay tube.

It is obvious that my invention is adapted to containers having varioustypes of walls,.and the embodiments shown herein areto be considered,therefore, asexamples only, of my method as practiced.

I claim:

1. In combination with an envelope having a narrow neck, means ithinsaid envelope for evaporating a'wall coating on the inner surfacethereof, and means for limiting the area covered by said wall coatingcomprising a rolled metal sheet of sufiicient sizeto enter saidjaarrowneck and of sufiicient resiliency to expand after insertion to covertheareas to be protected from evaporation.

- 2. The method of temporarily covering the inner wall of anenvelopehaving a narrow openingwith aresilient sheet during the evaporation ofmetalv therein which comprises rolling said sheet upon itself until theroll is of small enough diameter to enter the opening, releasing theroll toexpandsaid sheet to form a band covering an area of said wall,evaporating metal within said envelope, re-rolling said'sheet andvremoving it while rolled through said opening.

. BERNARD c. GARDNER.

